dentification of PIK 3 C 3 Promoter Variant Associated ith Bipolar Disorder and Schizophrenia

ackground: Genes involved in phosphoinositide (PI) lipid metabolism are excellent candidates to consider in the pathogenesis of ipolar disorder (BD) and schizophrenia (SZ). One is PIK3C3, a member of the phosphatidylinositide 3-kinase family that maps closely o markers on 18q linked to both BD and SZ in a few studies. ethods: The promoter region of PIK3C3 was analyzed for mutations by single-strand conformation polymorphism analysis and equencing. A case–control association study was conducted to determine the distribution of variant alleles in unrelated patients from hree cohorts. Electromobility gel shift assays (EMSA) were performed to assess the functional significance of variants. esults: Two polymorphisms in complete linked disequilibrium with each other were identified, -432CT and a “C” insert at osition -86. The -432T allele occurs within an octamer containing an ATTT motif resembling members of the POU family of ranscription factors. In each population analyzed, an increase in -432T was found in patients. EMSAs showed that a -432T ontaining oligonucleotide binds to brain proteins that do not recognize -432C. onclusions: A promoter mutation in a PI regulator affecting the binding of a POU-type transcription factor may be involved in BD nd SZ in a subset of patients.